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February 3, 2008

how to connect your digital still camera to a computer - explained

by sven at 11:59 pm

I just wrote a long email to a friend explaining how a Digital Still Camera might be connected to a computer. It seemed to me that this information might be useful to others, so I decided to repost it here.

If you haven't visited the Scarlet Letters blog before, please note that this is specifically intended for people who do stop-motion animation.


So, let's say you have a digital still camera and a computer. How do pictures get from your camera to the computer?

I'm going to answer the question "How do pictures get from your camera to your computer?" with another question: "How do you usually download your photos?" Usually when you take photos and then download them, they go through a USB cord.

But, how does the computer know to download them? Software. If you're using a Mac, you open up iPhoto and it recognizes that a camera is attached to the computer, and it downloads them for you. OR, you might have software that came with the camera that allows you to download the photos you took.

Now, certain software allows you to do something more than just download photos... It actually allows you to activate the camera's shutter by pushing a key on the computer. For Canon brand cameras (at least when I bought mine), this software is called RemoteCapture. The ability to snap off photos without touching the camera is something that we as stopmoes very much want -- because if we touch the camera to take a shot, we're going to very slightly move it -- and that messes up our shots.

A program like RemoteCapture can be used as a basic framegrabber. Whatever you can see in the LCD screen on the back of your camera, RemoteCapture can show you on your computer screen. This is a sort of "live out." You don't have niceties like onion skinning and toggling... But it can work OK.

Wouldn't it be nice if you could just use a USB cord to hook up your camera to the computer, and then turn on a framegrabber like FrameThief or Dragon? Well, too bad! It doesn't work, and here's why... Every brand of camera uses a different language to talk with the computer. Each kind of camera will only interface with the computer using a proprietary software. If you attach your camera to the computer with a USB cord, FrameThief won't know that there's a camera attached at all -- it has no way of talking to the alien device.

However, this may not be the case if you're using Dragon with a Canon or Nikon camera. Part of what's so exciting about Dragon is that the Caliris (as I understand it) have bothered to look into what language these cameras use, so Dragon can itself function as a RemoteCapture program.

(Just to remind you, the question is: "How do pictures get from your camera to the computer?")

Many digital still cameras have the ability to capture short videos. If you look at the side of your camera, there's probably a 1/8" wide hole somewhere marked AV. (It may be color-coded yellow.) What comes out of this hole?

Video can come out of this hole. And that's what a framegrabber wants to see. A framegrabber to be able to show you what the camera is looking at, and change the image in real time as you move the camera around.

But here's the problem. The signal that is coming out of that hole is analog, not digital. It's intended to be connected to a VCR -- not a computer. However, fortunately, there are ways to convert that analog signal to digital.

Let's take another look at that hole. Like I said, it's 1/8" in diameter. The cord that you're supposed to attach there is called an AV cord, and the other end of it should split into 3 connectors: red, white, and yellow. The red-white-yellow end is called "RCA." If you have a stereo, the red and white connectors may look very familiar -- they're the ones that carry the right and left signals for stereo sound. The yellow one carries video -- which is why the 1/8" hole may be marked with yellow.

OK, so let's say that you have yourself an AV cord (1/8" connector on one end, RCA on the other end). What can we connect the red-white-yellow end to? Like I said, you could connect it to a VCR -- but that does us no good. You could also connect it to an analog-digital converter, and from there send a digital signal into the computer.

You could buy a stand-alone analog-digital converter. The last time I checked (which was a while ago), they cost about $250. OR, you might be able to use a digital video camera. That's what I do. I have a Canon ZR45 DV cam, which does the job. Unfortunately, a DV cam that's being used as an analog-digital converter may not work for all digital still cams -- so you have to check.

Here's how I get my DV cam to work with the digital still cam and the computer... The DV cam can't accept the RCA cable directly; but it does accept an S-video cable in. So I went to Radio Shack and bought an RCA-to-S-video adaptor for about $30. It's about the size of an A battery. So, I've got an ugly chain of cables -- but it works to get the analog signal from my DSC into my DV cam: Digtital Still Camera -> AV cord -> RCA to S-video adaptor -> S-video cord -> DV cam.

From the DV cam to the computer is much easier -- I just need a FireWire cable. Make sure the settings on the DV cam are correct, and your framegrabber can now see what whatever would normally be showing on your DSC's LCD display. (It's worth noting that if I want to capture images using my DV cam, the FireWire is all I'll ever need.)

Are we ready to shoot films with the DSC? Not quite. There's one more important thing to deal with. See, the image that is being sent from the DSC to the computer is whatever you would normally see on the camera's LCD screen. That means the resolution is probably 640x480 pixels -- which is far less than what you were probably hoping for.

Understand that what you're seeing in the framegrabber is not what you're going to use for your final film -- it's just a preview that helps you take the "beauty shots." How do you capture the beauty shots? There are two solutions.

Solution #1: You can use a remote control to trigger the DSC's shutter, and capture all the images on the camera's memory card. Later on, you download the photos and assemble them into a film. There are two problems with this solution... You can only take as many photos as your camera's memory can hold... And, more significantly, it's a pain in the ass to delete a photo if you decide you made a mistake. Part of the whole point of having a framegrabber is being able to realize when you made a mistake, and backtrack by deleting some photos.... But if the beauty shots are all on the camera's memory card, you can't delete mistakes immediately -- you need to make a note for later, to delete the problem images after they've been downloaded.

Solution #2: You can run two programs at once: The framegrabber, and your camera's proprietary Remote Capture software. The framegrabber will save its files in one folder, and the Remote Capture software will save its (considerably larger) files in another. Each time you want to take a photo, you need to hit two buttons -- one in the framegrabber, one in the Remote Capture program. There are ways to make this somewhat simpler... You can create a script that will allow you to trigger both softwares simultaneously... But, as you can see, this actually requires a third piece of software to be running at the same time.

And, yes, this is what I actually bothered with when I shot my "A Word From Professor Ichbonnsen" short.

(Again, the question is: "How do pictures get from your camera to the computer?")

There is a more low-tech strategy for getting pictures into the framegrabber, a strategy which has worked for folks like Nick Hilligoss for years. That is: Attach a tiny spycam to the optical viewfinder of the camera.

As I mentioned in the previous section, the wiring for connecting a DV cam (or a digital spycam, or a webcam) to the computer is easy: all you need is a FireWire cable.

The image that your framegrabber uses will likely be a bit dark... And due to parallax, it won't be exactly what the DSC sees when it takes a shot -- but it's pretty close, and good enough to let you know that everything is in frame.

posted by sven | February 3, 2008 11:59 PM | categories: stopmo